Did Yamaha make a HPDI in 2001? What's difference in 2001 3.1L VMAX and HPDI?

Did Yamaha make a HPDI in 2001? What's difference in 2001 3.1L VMAX and HPDI? Who do these two Yamaha motors compare to a 2001 Mercury Optimax? http://www.bassboatcentral.com/smileys/USA1.gif

It depends on what size, their first few years out, there were only a few HPDI's out, not as many as now. In 2001 Yamaha did make an HPDI. Any VMAX HPDI is a direct injection motor, where a Yamaha VMAX without the HPDI is a carb motor.

If you are trying to figure out what is comparable to an Optimax, it would be an HPDI, as they are both direct injected motors. Hope this helps.

I thank you for the answer http://www.bassboatcentral.com/smileys/USA1.gif

Yamaha VMAX without HPDI could also have OX66 fuel injection....

Still new to this and trying to learn as much as possible but I have the 2001 3.1L VMAX 225 HP OX66. Is this a carb motor? I didn't think it was.

The OX66 motors are EFI.

The OX66 motors are electronic fuel injection ( like the old Chevy Throttle body injection). Basically computer controlled fuel and air sensors with injectors where the carbs were on the intake (one for each cylinder), that still mixes the fuel, air and oil thru the intake...IThey are very similar in principle the the Merc EFI's.

The HPDI motors are direct injected. The fuel is injected with individual injectors mounted in each cylinder and mixes with the air only during compression for a cleaner, more efficient burn. The Etec's, HPDI's and Opti's all use the same principle with different injection process's.